1. Field of the Invention
This invention relates to a method for preparing a coumarin compound, a chromene compound, and a method for preparing the chromene compound.
2. Description of the Related Art
Coumarins and derivatives thereof have biological activities including anti-carcinogenic activity, fungicidal activity, anti-coagulant activity, etc. For example, coumarin-3-(N-aryl) sulfonamides (see the following formula (I)) exhibit anticancer activity (see N. S. Reddy et al., Bioorg. Med. Chem. Lett. 14 (2004) 4093-4097 and Coumarin-3 (N-aryl) carboxamides (see the following formula (II)) can be used to arrest growth of breast cancer cells (see N. S. Reddy at al., Bioorg. Med. Chem. 13 (2005), 3141-3147).

In formula (I), X1 is 4-OCH3, 3-OH, 4-F, or 4-Br; and Y1 is 8-Br, 8-Cl, 8-OCH3, 8-OC2H5; in formula (II), X2 is H, 8-C2H5O, 6-Br, or 6-Cl; and Y2 is 4-Br, 4-I, 4-Cl, 3-NO2, or 3-NH2.
Another coumarin derivative known in the art is 3-methoxymethyl coumarin, which can be prepared from 3-chloromethyl coumarin by the following reaction (see J. Org. Chem., 1960, 25 (10), pp 1713-1716):

Preparation of 3-methoxymethyl coumarin can also be conducted by the following reaction (see J. Org. Chem., 1962, 27 (2), pp 696-698),
However, trifluoroacetic acid is extremely corrosive and generates a poisonous gas in the reaction, and chloromethyl ether (ClCH2OR) is a carcinogenic substance. Hence, the use of these compounds is likely to result in safety and health concerns.
Therefore, there is a need in the art to develop a process that is simple and safe in the preparation of a coumarin compound.